Telluraporphyrinoids: an interesting class of core-modified porphyrinoids

Alka, A.; Shetti, Vijayendra S.; Ravikanth, Mangalampalli

doi:10.1039/c9dt00079h

Cited by 21 publications

(29 citation statements)

References 49 publications

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“…Treatment of 4 with hydrochloric acid afforded vacataporphyrin 7 , and ditelluraporphyrins were used to prepare dideazaaporphyrins (divacataporphyrins). , Ditelluraporphyrins have also been used to generate metallaporphyrins such as 8a , b . Recently, investigations into telluraporphyrin-type structures have attracted renewed interest and new examples have been reported, including tellurabenziporphyrins and ditelluradiazuliporphyrins …”

Section: Introductionmentioning

confidence: 99%

Telluracarbaporphyrins and a Related Palladium(II) Complex: Evidence for Hypervalent Interactions

2021

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The reaction of a carbatripyrrin with a tellurophene dicarbinol in the presence of BF 3 •Et 2 O, followed by oxidation with DDQ, afforded the first example of a telluracarbaporphyrin. Although this system exhibits strongly aromatic characteristics, it is prone to air oxidation, giving rise to a hydroxy derivative that was characterized by X-ray crystallography. The initial telluracarbaporphyrin reacted with palladium(II) acetate to give a stable organometallic complex, and X-ray crystallography showed that the palladium cation was coordinated to all four atoms in the CNTeN core. An oxacarbatripyrrin was also reacted with a tellurophene dialcohol to give an air-stable porphyrin analogue with a CNTeO core. Nonmetalated telluracarbaporphyrins showed relatively short Te−N separations that strongly implied the involvement of hypervalent tellurium interactions. Furthermore, despite the presence of a very large tellurium atom, the tellurophene subunit is not strongly pivoted away from the mean macrocyclic plane as would be expected in the absence of these interactions. The aromatic properties of heterocarbaporphyrins were assessed by proton NMR spectroscopy, NICS calculations, and AICD plots. In addition, the relative stability of hydroxytelluraporphyrins in comparison to their tellurophene oxide tautomers was investigated and the aromatic characteristics of these oxidized structures were evaluated.

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Section: Introductionmentioning

confidence: 99%

Telluracarbaporphyrins and a Related Palladium(II) Complex: Evidence for Hypervalent Interactions

2021

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“…Interestingly, the tellurophene-containing dithiasapphyrin was not reported. Our group has recently focused interest in the synthesis and studies of tellurophene-containing porphyrinoids because of their unusual and unique properties . Herein, we report the synthesis of tellurophene-containing dithiasapphyrins, and our studies indicated that the tellurophene ring in telluro dithiasapphyrin is in the normal orientation facing toward the inner core unlike the other hetero dithiasapphyins, in which the corresponding heterocycle was inverted and facing outward from the macrocycle core.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Studies of Core-Modified Tellura Dithiasapphyrins

2022

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Four different aromatic meso-substituted tellurophene-containing dithiasapphyrins were synthesized by acid-catalyzed [3+2] condensation of 16-telluratripyrrane with bithiophene diol in 22–23% yields. The structural, spectral, and electrochemical properties of tellura dithiasapphyrins were studied and compared with those of previously reported aza (pyrrole)- and other heterocycle (furan, thiophene, and selenophene)-containing dithiasapphyrins. Nuclear magnetic resonance studies indicated that the tellurophene ring in tellura dithiasapphyrins is in the normal conformation, facing toward the inner core, but flips in diprotonated derivatives to an inverted conformation, facing away from the macrocyclic core, unlike aza- and other heterocycle-containing dithiasapphyrins in which pyrrole and the corresponding heterocycle ring always prefer to be in inverted conformation in their neutral and protonated forms. The crystal structure obtained for one of the tellura dithiasapphyrins showed that the macrocycle is highly planar and the tellurophene ring is in the normal conformation. The absorption spectra of tellura dithiasapphyrins exhibited slight hypsochromic shifts compared to those of pyrrole- and other heterocycle-containing dithiasapphyrins. The redox studies indicated that the tellura dithiasapphyrins are electron deficient and readily undergoes reductions. Density functional theory and nuclear independent chemical shift studies indicated that the macrocycles are aromatic, and the computational results closely matched the experimental observations.

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“…Heteroporphyrins resulted from replacing one or two pyrrole Ns with other heteroatoms − such as O, S, Se, Te, C, Si, and P, which exhibit interesting physicochemical properties that are different from tetrapyrrolic porphyrins. Thus, substituting pyrrole ring(s) of porphyrins with other heterocycles such as furan, thiophene, selenophene, tellurophene carbacycle, etc.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Properties of Dibenzothiophene Embedded Heteroporphyrins

Sinha

Ravikanth

2021

J. Org. Chem.

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A series of new stable dibenzothiophene embedded heteroporphyrins were synthesized in 6–7% yields by condensing 1 equiv of dibenzothiophene-based tripyrrane with 1 equiv of four different diols, 2,5-bis(hydroxymethyl)heterocycles (furan, thiophene, selenophene, and tellurophene), under mild acid-catalyzed conditions in CH2Cl2. The formation of dibenzothiophene embedded heteroporphyrins was confirmed by high-resolution mass spectrometry and thoroughly characterized by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, absorption, electrochemical, and density functional theory/time-dependent density functional theory (DFT/TD-DFT) studies. The NMR studies indicated that the macrocycles were nonaromatic in nature. The electronic properties of the macrocycles were significantly altered as the heterocycle of the macrocycles was varied from furan to thiophene, selenophene, and tellurophene, as reflected clearly in the spectral and electrochemical properties. The macrocycles exhibited a sharp band in the region of 420–440 nm and a relatively broad absorption band(s) in the higher wavelength region of 550–800 nm. The oxa analogue was considerably blue-shifted as compared to the other macrocycles, whereas the tellura analogue exhibited relatively broadened and red-shifted absorption bands. Upon protonation of these macrocycles, the resulting diprotonated species displayed bathochromically shifted absorption bands, which were extended to the NIR region. DFT studies revealed that the macrocycles were highly distorted and strained and exhibited half chair conformation with restricted π-conjugation and confirmed their nonaromatic nature due to the lack of planarity of the macrocycle. TD-DFT studies were in agreement with the experimental spectral and electrochemical results.

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Telluraporphyrinoids: an interesting class of core-modified porphyrinoids

Abstract: This perspective presents a concise overview of the developments in telluraporphyrinoid chemistry since its inception.

Cited by 21 publications

References 49 publications

Telluracarbaporphyrins and a Related Palladium(II) Complex: Evidence for Hypervalent Interactions

Telluracarbaporphyrins and a Related Palladium(II) Complex: Evidence for Hypervalent Interactions

Synthesis and Studies of Core-Modified Tellura Dithiasapphyrins

Synthesis and Properties of Dibenzothiophene Embedded Heteroporphyrins

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